Nature maintains remarkable control over the nanostructure of structural biopolymers, such as silks, elastic, collagen, keratin, and amelogenin, through the manipulation of primary polypeptide sequences to achieve desired functionality. Not only do such natural biopolymers precisely fit their purpose, but in many cases, these materials have a multitude of attributes, each of which is optimized. For example, spider silk is a water-insoluble fiber with outstanding strength and toughness, properties usually considered to be mutually exclusive, that is spun at close to ambient conditions using water as the solvent. Moreover depending on the composition, this silk can be highly elastic or inelastic. These unique combinations of properties are inherently necessary to protect the web from bombardment with foreign objects and the impact energy generated by insects colliding and becoming ensnared in the web. Silkworm silk also has many of these highly desirable mechanical properties. All of these silks are very durable and resistant to degradation.
Applications for fibers or films having the attributes of structural biopolymers, such as spider or silkworm silk, include uses such as tissue-engineering scaffolds, cell-culture substrates, biocompatible coatings, sutures, membranes, grafts, and drag delivery systems among others. However, it is not cost-effective to attempt to harvest the naturally occurring silks for these purposes.
It is therefore an object of this invention to provide synthetic polymers having properties comparable or superior to naturally occurring structural biopolymers, such as silks.
It is another object of this invention to provide fibers and films having high strength and toughness comparable or superior to naturally occurring structural biopolymers, such as silks, that are capable of large-scale production.